PROJECT SUMMARY/ ABSTRACT This is a renewal application from Columbia University Irving Medical Center to obtain continued support for our post-doctoral training program Training in Pediatric Infectious Diseases. Dr. Lisa Saiman and Dr. Alice Prince will be the PDs/PIs under the multi-PI model. Both are established investigators with complementary research interests. Both have long-standing commitments and experience training young physician scientists from many disciplines and a long track record of success. The goal of this training grant is to train post-doctoral fellows (MDs or MD PhDs) in state-of-the-art multidisciplinary research training in Pediatric Infectious Diseases in order to develop research careers in basic, translational, clinical, and/or epidemiologic investigation in academic settings and/or in the public health sector. The research focus of the training program reflect three complementary, overlapping areas of research involving Host-Pathogen Interactions: microbial pathogenesis, immune responses to microbial pathogens, and public health/ healthcare delivery to address microbial pathogens. We are requesting 5 more years of funding for 3 post-doctoral fellow trainees per year. We have chosen highly collaborative, multdisciplinary faculty with expertise in Host-Pathogen Interactions to serve as training preceptors. We are expanding our applicant pool to include trainees from other pediatric disciplines who choose to pursue infectious diseases research relevant to their subspecialty area. The training grant will support the trainees during their 2nd and 3rd year of subspecialty training during time which they will be engaged in scholarly research guided by an experienced mentor. Drs. Saiman and Prince will be supported by feedback from the Internal and External Advisory Committees, and committees focused on Trainee Recruitment/Selection, Research/Mentorship and Career Development. This training program is unique at our institution and will allow us to train future academic leaders.